1. Field of the Invention
This invention relates to an optical coordinates inputting apparatus adapted to reduce power consumption during a period that the operation of inputting coordinates is not executed.
2. Description of the Prior Art
An optical coordinates inputting apparatus is disposed on the front face of an image display unit, such as a CRT display or an LCD, etc. for use in inputting coordinates to a microcomputer or the like. The inputting apparatus is constructed to arrange a light emitting element array and a photodetector array opposed to the light emitting element array in X- and Y-axis directions on the outer periphery of the front surface of a screen, such as a CRT display, to sequentially selectively drive to scan the light emitting elements and the photodetectors by multiplexer means, and to output a coordinates signal of a position where a light signal outputted from the light emitting element is interrupted by a finger of inputting the coordinates when the light signal outputted from the light emitting element is interrupted by the finger by the driving scan so that the opposed photodetector cannot photodetect the light signal to produce a coordinates input by the calculation of the microcomputer.
The surface on which the light emitting element array and the photodetector array are arranged is disposed in coincidence with a Z-axis direction in the X- and Y-axis directions, or disposed to be displaced in a Z-axis direction as disclosed in Japanese Patent Laid-open No. 139606/1982. The light emitting element array and the photodetector array of the X- and Y-axis directions are so constructed as to simultaneously drive to be scanned in both the X- and Y-axis directions by multiplexer means or to drive to be first scanned in either one of the X- and Y-axis directions and subsequently scanned in the other direction after the first driving scan is finished.
In the conventional optical coordinates inputting apparatus as described above, the light emitting element array and the photodetector array of the X- and Y-axis directions are driven to be scanned simultaneously in both the X- and Y-axis directions or alternately.
In order to produce an X-axis coordinates signal and a Y-axis coordinates signal, the light emitting element array and the photodetector array of the X- and Y-axis directions are driven to be scanned when the coordinates are inputted. In order to further reduce the power consumption of the apparatus, it is desirable to eliminate the driving scan of the light emitting element array and the photodetector array as much as possible during a period that the coordinates are not inputted. In addition, when the light emitting element array and the photodetector array are not driven to be scanned during the period that the coordinates are not inputted, the operating frequencies of the light emitting element array and the photodetector array decrease to thus increase the lives of the arrays.